Detergents or cleaning agents, cosmetic agents, adhesives or printing inks typically contain scents that impart a pleasant smell to the products. The scents not only mask a potential odor of other ingredients, but also produce a pleasant smell impression in the consumer.
Scents are important components of the composition, in particular in the field of detergents and cleaning agents, since laundry should have a pleasant and substantially fresh smell when damp as well as when dry.
The fundamental problem one faces when using scents in detergents or cleaning agents, cosmetic agents, adhesives or printing inks is that, despite the scents being substantially volatile compounds, it is still desirable to produce a long-lasting scent effect. In particular when using scents that represent fresh and light notes of the perfume and, due to the high vapor pressure thereof, vaporize particularly quickly, the desired long-lasting nature of the scent impression is difficult to achieve.
One option for the delayed release of scents is the use of what are known as photo-activatable substances as pro-fragrances. The action of sunlight or other electromagnetic radiation having a certain wavelength induces the cleavage of a covalent bond in the pro-fragrance molecule, whereby a scent is released.
In this connection, WO 2011/101179 A1 discloses special ketones as photo-activatable substances, which in the presence of sunlight release a scent comprising at least one cyclic double bond in a photochemical fragmentation process.
Starting from the scent, the described pro-fragrances are prepared in a two-stage synthesis by hydroboration of the at least one cyclic double bond and a subsequent substitution reaction.
One disadvantage of the synthesis method described in WO 2011/101179 A1 is that scents, which in addition to the at least one cyclic double bond, also include one or more semicyclic and/or exocyclic double bonds, cannot be selectively reacted, or cannot be reacted at all, to yield the desired pro-fragrances, since the sterically least hindered double bond is the first to react during hydroboration of the scent. One disadvantage of these undesirable constitutional isomers is that they are cleaved only inadequately, or not all, upon irradiation with light and do not release the stored scent.
It was therefore the object of the present invention to provide a simple method for selectively preparing a pro-fragrance that not only ensures effective release of the stored scent, but also stores scents which, in addition to at least one cyclic double bond, can comprise further semicyclic and/or exocyclic double bonds.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.